Some modern computer systems utilize multiple processing units, such as central processing units (CPUs), graphics processing units (GPUs), or other systems on a chip (SoCs), that are able to communicate with each other through a communication interface, such as HyperTransport (HT). As an example, HT is a high-bandwidth bidirectional serial/parallel bus that allows the multiple processors to communicate in point-to-point fashion with each other, or with other devices.
However, in such systems, uncooperative behavior of one or more of the SoCs or other devices in the system (whether resulting from poor design, bugs, or malicious intent) could negatively impact performance of cooperating SoCs or devices. For example, such devices could cause denial-of-service (DOS) attacks and other problems if they are allowed to issue excessive memory requests or other traffic into other SoCs through the external interface (e.g., HT) without any constraints.